不松懈警觉的

例句：

1. 1. The police were alert for any suspicious activity in the area.
   警方对该地区任何可疑活动保持高度警惕。
2. 2. She was always alert to her surroundings, making her a good observer.
   她总是对她周围的环境保持警惕，使她成为一个优秀的观察者。
3. 3. The driver was alert when he saw the oncoming car.
   司机在看到迎面而来的汽车时保持警惕。